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Patented Mar. 10, 1931 UNITED STATES/PATENT OFFICE" WOLFGANG J'AECK AND JOSEPH LANG, F BASEL, SWITZERLAND, AS SIGNORS TO THE FIRM. SOCIETY OF CHEMICAL INDUSTRY IN BASLE, OF BASEL'SWITZERLAND PRODUCTION OF FAST TINTS ON AGETYL CELL'ULOSE No Drawing. Application filed November 3, 1925, SerialNo. 68,839, and in Switzerland Novemberv 12, 1924.

v It is known that insoluble dyestuffs, such as'for instance certain unsulfonated azodyestuffs, indophenols, anthraquinone derivatives etc. may be employedfor the production of tints on acetyl cellulose. For this purpose however the products in question have to be brought in to a fine state of subdivision. This may be done, either by boiling the dyestufl paste with soap solutions in presence of sodium carbonate and of an insoluble organic solvent as for example tetraline of the formula,

H H n H H H H or by grinding the dyestuffswith the salts of sul onated oils such as Turkey red oil. The latter of the two-processes, which is much more simple than the first one, is bound how- 2 ever to the use of the rather expensive Turkey red oil or its analogues.

According tothe resent invention it has been found that emu sions of dyestuffs which are obtained by mixing amino-azo-dyestufis having afiinity for acet 1 cellulose with waste sulfite liquor, are wel adapted to produce tints on acetyl cellulose, ieldmg, especiallyin presence ofsoaps or sul onated soaps, as Turey red oil, dyebaths which dye acetyl cellulose or acetyl cellulose silk very uniform tints fast to rub water, washing and, in some cases, to light.

The process of the invention offers with regard to the methods already known the advantage of being simple and inexpensive. Itv

could not be foreseen, for, according to the British Patent 214,330, the addition of waste sulfite liquor to the dyebath is recommended on the contrary for the dyeinlg of union fabrics from cotton and acetyl ce ulose silk with sulfur dyes, in order to prevent the dyeing of the silk.

7 Emmplal 500gramsofapaetefromparteof o-aminoazotoluene and 80 parts of waste sulproperties of fite liquor of strength are mixed intimately with 10 liters of water of 50 and as many liters of concentrated soap solution as are necessary to obtain afterwards a dyebath containing 2 parts per thousand of soap. The mixture is then diluted with cold water to about 300 liters 10 kilograms of acetyl cellulose silk yarn are introduced into the dyebath thus obtained, worked, the dyebath brought to .within of an hour, and the goods dyed further for 15 minutes at this temperature. The yarn is then rinsed and brightened as usual. There are thus obtained strong bright fyellow tints with very good astness.

In an analogous manner are treated other amino-azo-dyestufls, yielding thus the most various colours from greenish-yellow (aminoazobenzene) to red, violet and bluish-violet azodyestu s from nitranilines and naph t ylamines or aminonaphthols).

The process described in the example above is adaptedto fabrics from cotton-acct l cellulose silk or viscose-acetyl cellulose sil for union fabrics, however, containing besides acetyl cellulose animal fibres, such as wool or natural silk, it is preferable not to add any soap while preparing-the ((liyebath. Infthis case it maybe dyed in an aci bath, if the constitution of the dyestufis rees with it, without impairing the colloida state and the capacit of dyemg.

' at we claim is:

The herein described process for the roduction of, tints on acetyl cellulose, w ch com risesj treating the acetyl cellulose with a co oidal preparation from an intermixture of' insoluble amino-azo-dyestufl's having an afinity for acetyl cellulose with waste sulfite n witness whereof we have hereunto signed our names this 19th day of October 1925. 

